Erigeron canadensis

Erigeron canadensis L., Sp. Pl. 2: 863. 1753 (as E. canadense); Hook. f., Fl. Brit. Ind. 3: 264. 1882; Nair, Fl. Bashahr. Himal. 152.1977; Dhaliwal & Sharma, Fl. Kullu Dist. 371. 1999; Kaur & Sharma, Fl. Sirmaur 377. 2004; Singh & Sharma, Fl. Chamba Dist. 409. 2006; Conyza canadensis (L.) Cronq., Bull. Torrey Bot. Club 70: 632. 1943; Fl. North. Amer. @ eFloras.org 20: 350; Conyza canadensis var. glabrata (A. Gray) Cronq., Bull. Torrey Bot. Club 74: 150 (1947 C. canadensis var. pusilla (Nuttall) Cronq., Bull. Torrey Bot. Club 74: 150 (1947).

Annuals, erect, 50-200(-350+) cm tall (in flowering condition), simple or branched mostly distally, lateral branches shorter than main axis, stem ribbed, hirsute, densely leafy. Leaves alternate, sessile or subsessile, 2-6(-10+) cm x 4-10 mm, proximal leaves oblanceolate to linear, acute, shortly apiculate; distal leaves smaller, entire; faces usually glabrous, proximal margins +/- ciliolate, hairs usually stiff, erect, spreading and hispid on nerves. Capitula radiate, ca. 7 mm long and 5-6 mm across, numerous, on 2-10 mm long slender peduncles, combined into much branched leafy panicles, sometimes corymbiform arrays. Involucres subcylindric, 3-4 mm long; phyllaries many, 2-3-seriate, greenish, linear, lanceolate to linear- lanceolate, acute; outer +/- 1.5 mm long, inner 3-3.3 mm long; usually glabrous, sometimes sparsely strigose abaxially, margins chartaceous to scarious; phyllaries deflexed after dehiscence of cypselae. Receptacles 1-1.5 (-3) mm diameter in fruit. Ray florets: 20-30 (-45+) in more than 1-series, 2.5-3 mm long, filiform, pistillate, fertile. Corolla ligulate, 2.2-2.7 mm long, slightly longer than disc florets, white, pale rosy or purplish, corolla tube longer than limb, apex 2-denticulate. Disc florets: (3-) 8-30+, 2.5-3 mm long, yellowish. Corolla 2.2-2.6 mm long; tube sparsely puberulent; limb 5-lobed. Cypselae uniformly pale tan to light grey-brown, 1-1.5 mm long, oblong, angular, sparsely strigillose or glabrous. Pappus hairs 15-25, 1-seriate, connate at base, 2-3 mm long, scrabrid, dirty white.

Flowering and Fruiting: February to June
Common Names: Canadian Horseweed, Horseweed, Canadian Fleabane, Coltstail, Marestail, Butterweed